Abstract: A low-price, compact oscillating device having a good temperature characteristic of a frequency intermediate between a temperature compensated crystal oscillator (TCXO) and an oven-controlled crystal oscillator (OCXO) is provided. The oscillating device having a TCXO is provided with a base on which the TCXO is mounted, that is formed into a box shape having a recess, with a plane area substantially equal to that of the TCXO; and a semiconductor chip including a temperature control circuit, a temperature sensor, and a heating element, mounted in the recess. An opening of the recess is provided in a surface opposite a surface in which the temperature compensated crystal oscillator is mounted, and sealed by a cover. A temperature of the TCXO can be kept constant to provide a oscillating device having an excellent temperature characteristic of a frequency compared with the single TCXO.

Abstract: A voltage control type temperature compensation piezoelectric oscillator, includes: a voltage control type oscillation circuit; an automatic frequency control (AFC) circuit outputting a control voltage for controlling an oscillation frequency of the voltage control type oscillation circuit based on an external control voltage; a temperature compensation voltage generating circuit generating a temperature compensation voltage; and a gain variable circuit varying a gain of the temperature compensation voltage. In the oscillator, the gain variable circuit is controlled by the control voltage outputted from the AFC circuit, and the oscillation frequency of the voltage control type oscillation circuit is controlled by an output voltage of the gain variable circuit.

Abstract: A constant-temperature type crystal oscillator includes: a crystal unit including a case main body including a first power source terminal on an outer bottom surface thereof; a surface-mounted oscillator; a temperature control circuit including a heating resistor and a temperature sensor; and a circuit substrate including a second power source terminal. One ends of the heating resistor and the temperature sensor are electrically connected to the second power source terminal. The first power source terminal of the surface-mounted oscillator and the one ends of the heating resistor and the temperature sensor are electrically connected to the second power source terminal of the circuit substrate. The first power source terminal of the surface-mounted oscillator is directly and electrically connected to, at least, the one end of the temperature sensor via an electrically-conducting path.

Abstract: The integrated circuit package includes a processing core for operating on a set of instructions to carry out predefined processes. A real time clock circuit provides a system clock for the processing core. The real time clock further comprises an internal oscillator that generates the system clock for the integrated circuit package. The internal oscillator has a factory calibrated bias current. An internal oscillator control register controls the operation of the internal oscillator responsive to control bits of the programmable load capacitor array controlled by the processing core.

Abstract: A period signal generator comprises a first period signal generating unit for generating a first period signal of which period changes according to a temperature, a second period signal generating unit for generating a second period signal which has a constant period regardless of a temperature, and a period signal output control unit for comparing the first period signal with the second period signal and selecting and outputting the first period signal in case that the period of the first period signal is shorter than that of the second period signal.

Abstract: Systems and methods for implementing a temperature compensated two-stage ring oscillator are described. At least one embodiment includes a system for generating a clock signal comprising a self-starting oscillator comprising two delay stages in a ring configuration. The two-stage ring oscillator is configured to generate the clock signal, wherein the delay stages are configured such that the two-stage ring oscillator has a single right-half plane (RHP) pole in each of the two delay stages where feedback is always positive. For some embodiments, the system further comprises a compensation module configured to sense temperature and process variations and adjust a supply voltage for the two-stage ring oscillator to compensate for temperature and process variations in order to maintain a constant frequency clock signal. For such embodiments, the compensation module comprises a replica circuit configured to mirror operation of the n-channel devices within the two-stage ring oscillator.

Abstract: A crystal oscillator in which phase noise is reduced includes: a resonance circuit having a crystal unit and split capacitors connected to the crystal unit; a transistor for oscillation having a base connected to the connection node of the crystal unit and the split capacitors; an output line for connecting the node for connecting together the split capacitors and the emitter of the transistor; a crystal resonator inserted in the output line; and a resistor connected in parallel to the crystal resonator.

Abstract: A system and method for generating a highly stable holdover clock utilizing an integrated circuit and an external OCXO is presented. The integrated circuit comprises an input reference clock receiver, a phase and frequency detector that generates an error signal between the input reference clock signal and a feedback clock signal, a data storage block that stores model parameters to predict frequency variations of the OCXO, an adaptive filtering module that includes a digital loop filter and algorithms for updating the model parameters and predicting frequency variations based on the model, a switch that enables the system to operate in normal or holdover mode, a digitally controlled oscillator, and a feedback divider.

Abstract: Techniques of compensating frequency in an output in reference to a reference frequency signal are disclosed. The reference frequency signal may be from a crystal oscillator or other oscillators. Due to the changes of the temperature, the reference frequency signal drifts. According to one aspect of the techniques, a temperature frequency correction word is generated in accordance with a frequency compensation value in view of a current temperature to generate a substantially temperature compensated frequency output from a reference frequency signal. The frequency control word is produced from a successive approximation circuit configured to produce the temperature frequency correction word in accordance with the frequency compensation value in view of the current temperature. Both the temperature frequency correction word and a frequency control word are data represented in a sequence of bits. As a result, the compensated frequency output can be of high precision.

Abstract: A device and a method for generating a output clock signal having a output cycle, the method includes: (i) adjusting a delay of an adjustable ring oscillator to provide a high frequency clock signal having a short cycle so that the output cycle substantially equals a sum of integer multiples of a sleep cycle and integer multiplies of the short cycle; wherein the output cycle differs from any integer multiples of the sleep cycle; wherein the sleep cycle characterizes a sleep clock signal that is generated by a low frequency sleep clock; wherein the short cycle is shorter than the sleep cycle; (ii) counting short cycles and sleep cycles; and (iii) generating, during a sleep mode, in response to the counting and to a predefined counting pattern, the first clock signal; wherein the generating includes activating the adjustable ring oscillator only during a portion of a single sleep cycle per each output cycle.

Abstract: A constant-temperature type crystal oscillator includes: a crystal unit including a case main body, in which two crystal terminals and two dummy terminals are provided on an outer bottom face thereof, and a crystal element housed in the case main body; an oscillator output circuit including an oscillating stage and a buffering stage; a temperature control circuit for keeping an operational temperature of the crystal unit; and a circuit substrate, on which circuit elements of the crystal unit, the oscillator output circuit and the temperature control circuit are installed. The temperature control circuit includes: heating chip resistors; a power transistor; and a temperature sensing element. The dummy terminals are connected to a circuit terminal for dummy on the circuit substrate. The circuit terminal for dummy is connected to an electrically-conducting path, to which one terminal of the heating chip resistors is electrically connected, on the circuit substrate.

Abstract: Methods and apparatus for controlling frequency in a crystal oscillator are provided that allows for continued reception of GPS signal solution in a continuous high G environment. One method comprises measuring G-forces asserted on the crystal oscillator, determining a shift in frequency of the crystal oscillator due to the measured G-forces, determining a temperature that would shift the crystal oscillator's frequency back to a rate that would occur without the measured G-forces, and changing the temperature of the crystal oscillator based on the determined temperature to shift the crystal oscillator's frequency back to a rate that would occur if the G-forces were not present.

Abstract: The invention discloses a varactor device (100) for improved temperature stability, comprising a first varactor (160) connected to a decoupling network (150). The device further comprises a voltage stabilizer (110), said stabilizer comprising a capacitor (140) and a temperature dependent capacitor (130), and in that the stabilizer comprises means for connection to a DC-feed (120). Suitably, the decoupling network (150) is connected in parallel to the first varactor (160), and the capacitor (140) of the voltage stabilizer (110) is connected in parallel to the decoupling network (150), the temperature dependent capacitor (130) of the voltage stabilizer (110) being connected in series to the diode of the voltage stabilizer (110).

Abstract: Provided is an oscillator including: a MEMS resonator for mechanically vibrating; an output oscillator circuit for oscillating at a resonance frequency of the MEMS resonator to output an oscillation signal; and a MEMS capacitor for changing a capacitance thereof caused by a change in a distance between an anode electrode and a cathode beam according to an environmental temperature.

Abstract: A system for acquiring logging data comprises a controller for causing the generation of a signal in a formation surrounding a wellbore. The controller has a first clock for time-stamping a record of the generated signal. A receiver is deployed in the wellbore and is adapted for detecting the signal. A second clock comprises a double-oven surrounding a crystal oscillator. A controller is operatively coupled to the double-oven to maintain the crystal oscillator temperature substantially at the crystal oscillator turnover temperature. The second clock is synchronized with the first clock before deployment in the wellbore, and the receiver references the second clock in order to record a time-stamp associated with the detected signal.

Abstract: A circuit for generating a clock of a semiconductor memory apparatus is provided. A reference voltage generator is configured to generate a reference voltage. A reference current generator is configured to generate a reference current that has a constant current value regardless of a change in temperature. An oscillator is configured to receive the reference voltage and the reference current to generate a clock that has constant frequency.

Abstract: An oven controlled crystal oscillator capable of uniformly transmitting heat from the heat generator to improve the frequency-temperature characteristics. The oven controlled crystal oscillator includes a high thermal conductivity plate having high thermal conductivity and provided on one side of a substrate, where the crystal resonator is provided, in such a manner to contact the resistors, the transistor, the crystal resonator, and the temperature sensor. This structure can transmit heat from the resistors and the transistor as the heat generator to the crystal resonator and the temperature sensor rapidly with less heat loss to assure a uniform temperature inside the substrate, thereby improving the frequency-temperature characteristics.

Abstract: An oscillator includes an oscillator circuit and a resonator that produces an output frequency. A temperature compensation circuit is coupled to the oscillator circuit. The temperature compensation circuit stabilizes the output frequency in response to changes in temperature. At least one temperature sensor and a temperature sensor signal modification circuit are coupled to the temperature compensation circuit. The temperature sensor signal modification circuit receives a temperature signal from the temperature sensor and generates a modified temperature sensor signal that is transmitted to the temperature compensation circuit.

Abstract: A crystal oscillator in which a temperature characteristic of an oscillation frequency is improved to omit a measurement operation of the temperature characteristic of the oscillator, and manufacturing is facilitated to reduce a manufacturing time. In the crystal oscillator, a power voltage is applied to a collector of a transistor via series connection of an inductor for resonance and a resistance, a crystal unit is disposed in a loop which returns to an emitter of the transistor from a point between the inductor L4 and the resistance, and further, in the loop, a first parallel circuit in which a stationary capacitor having a negative temperature coefficient and a stationary capacitor having a zero temperature coefficient are connected in parallel with each other is inserted between an oscillation output taking point and the collector.

Abstract: A free running clock circuit includes a switching circuit for switching between first and second logic states at a predetermined frequency based upon a trip voltage. The switching circuit has an inherent temperature profile associated therewith. A voltage divider circuit outputs a defined trip voltage that is compensated over the temperature to offset the temperature profile of said switching circuit to provide an overall temperature compensated operation for the free running clock circuit. The voltage divider circuit has a top programmable resistor array connected in series with at least two programmable resistor arrays between two supply terminals of differing voltages.

Abstract: A real time clock integrated circuit (RTC IC) and an electronic apparatus thereof are provided. In the RTC IC, only a low-power oscillator is used for generating a standard clock for a real time counter, and the standard clock with a frequency drift of the low-power oscillator is compensated through table lookup. Accordingly, the power consumption, fabrication cost and design complexity of the RTC IC are reduced and the counting operation duration of the RTC IC is prolonged.

Abstract: A temperature correcting apparatus divides an actually measured waveform of correcting voltages, which are required at each of different temperatures, by a minimum resolution of D/A conversion; obtains voltage digital values representing voltage values at individual dividing points of the actually measured waveform, and obtains times corresponding to the voltage digital values; prestores pairs of the voltage digital values and times together with addresses as correcting data; reads out the correcting data in response to the detection address representing the temperature; extracts or calculates from the correcting data the voltage digital values and times about the correcting voltages required by the detection address; and sequentially supplying a D/A converter (36) with the resultant voltage digital values in synchronization with the corresponding times.

Abstract: A clock generator includes a ring oscillator for outputting a basic signal, a divide-by-N frequency divider for dividing the basic signal by a division ratio N to generate a clock signal having a target frequency, a divide-by-two frequency divider for dividing the clock signal by two when an enable signal is on, a counter for counting the number of pulses of the basic signal for a predetermined period of time, a calculator for calculating the division ratio N, and a comparator for comparing a count value of the counter with a threshold value. When the count value of the counter is less than the threshold value, the comparator turns on the enable signal. Thus, when a temperature of the ring oscillator increases, the frequency of the clock signal is reduced to half the target frequency.

Abstract: A device for generation of a reference frequency includes a component configured for generating a reference voltage, and a slaving circuit configured for slaving the reference frequency to the reference voltage.

Abstract: A phase lock loop pre-charging system and method are described. In one embodiment, a phase lock loop pre-charge system includes a bias component for generating a pre-charge voltage, and an activation component for activating the bias component. In one exemplary implementation the pre-charge voltage is utilized to facilitate pre-charging of a phase lock loop voltage controlled oscillator. In one embodiment, the bias component includes replica bias components that track the voltage controlled oscillation control voltage over varying process, voltage and temperature characteristics. The phase lock loop pre-charging systems and methods can be utilized to reduce lock time for a circuit.

Abstract: A phase frequency detector compares a reference clock signal to a feedback clock signal to generate pulses in one or more output signals. The one or more output signals have a minimum pulse width. The phase frequency detector has a temperature sensing circuit. The phase frequency detector adjusts the minimum pulse width of the one or more output signals using the temperature sensing circuit to compensate for variations in the temperature of the phase frequency detector.

Abstract: A first order function generation circuit receives a signal from a temperature sensor circuit, and generates a first order function control signal V1 that is affected by the ambient temperature. A fourth order and fifth order approximation function generation circuit receives signals from the temperature sensor circuit and from the third order approximation function generation circuit, and generates a fourth and fifth order approximation function control signal V45 that is affected by the ambient temperature. A peak change point adjustment circuit outputs a signal to adjust the value of a peak change point temperature Ti for the third order approximation function generation circuit, the first order generation function circuit and the fourth order and fifth order approximation function generation circuit. A temperature compensation circuit adds together control signals V0, V1, V3 and V5, and outputs the resultant signal Vc.

Abstract: A differential amplifier circuit includes: a differential transistor pair composed of first and second transistors; a first resistance connected to a junction point of the first and second transistors at one terminal and to a first voltage node at the other terminal; second and third resistances provided between the first and second transistors, respectively, and a second voltage node; and first and second passive circuits respectively connected to the second and third resistances, the load characteristics of the passive circuits changing according to a control signal supplied. A ring oscillator is composed of a plurality of such differential amplifier circuits connected in a loop.

Abstract: The invention relates to a proximity switch, particularly an inductive proximity switch, with an oscillator having an at least partly self-compensated feedback network influenceable by a target to be detected, as well as an oscillator amplifier.

Abstract: An oscillator system may include an oscillator block having a plurality of inputs and outputting a clock signal, a frequency divider block receiving the clock signal and outputting a divided clock signal, a tuning block receiving the divided clock signal and outputting a comparison signal, and a control block coupled to the tuning block. The control block may receive the comparison signal. The control block may include a configuration block for producing a plurality of outputs for the corresponding inputs of the oscillator block, and an Up/Down counter having outputs applied to the configuration block.

Abstract: An integrated circuit fabricated in a multiple oxide process can be used to provide a temperature-insensitive circuit. The temperature-insensitive circuit can be a ring oscillator; this ring oscillator can be used as a low-cost integrated reference frequency to monitor and to modify the behavior of the integrated to produce the desired results. In some embodiments, the reference oscillator output can be compared to second oscillator output where the second oscillator performance is temperature-sensitive. The comparison result can be monitored and processed to power down the integrated circuit.

Abstract: An oscillator circuit is provided having an oscillating amplifier circuit connected to a resonator. The oscillator/amplifier and resonator are preferably fabricated on a single die using semiconductor fabrication tools. Included with the circuitry is a temperature sensor or transducer, an execution unit, non-volatile memory, a modulator, and frequency synthesizer, all of which are integrated together on the substrate, along with the piezoelectric crystal resonator. The frequency synthesizer can preferably include a phase-locked loop with a divider that is in a feedback loop of the phase-locked loop, in which a divide-by value is received from a modulator that achieves finer and higher resolution frequency selectivity from the voltage-controlled oscillator, also within the phase-locked loop, as an output from the crystal oscillator.

Abstract: A voltage-controlled oscillator has an oscillation frequency controlled through a voltage applied across ends of a variable-capacitance element. The voltage-controlled oscillator has a frequency control bias circuit which applies to a first end of the variable-capacitance element a voltage for frequency control according to a control voltage, a first current source which generates a first current according to the control voltage, a second current source which generates a second current according to temperature, independent of the control voltage, a converting resistor which converts a current, obtained by adding together the first and second currents, into a voltage, and a temperature compensation bias circuit which applies to the second end of the variable-capacitance element a voltage for temperature compensation according to the voltage produced by the converting resistor.

Abstract: A feedback loop, such as a phase-locked loop, on an integrated circuit has a detector, a charge pump, and a loop filter. The charge pump adjusts its output current in response to variations in a process of the integrated circuit to reduce variations in the loop bandwidth. The charge pump also adjusts its output current in response to variations in a resistance of a resistor in the loop filter to reduce variations in the loop bandwidth. The charge pump can also adjust its output current in response to variations in a temperature of the integrated circuit to reduce variations in the loop bandwidth. A delay-locked loop on an integrated circuit has a phase detector and a charge pump. The charge pump adjusts its output current in response to variations in the temperature and the process of the integrated circuit to reduce changes in the loop bandwidth.

Abstract: Precision integrated time reference circuits are disclosed. Preferred embodiments provide time reference circuits that are relatively insensitive to variations in process, supply, and temperature. A preferred embodiment of the invention is disclosed in which a relaxation oscillator according to the invention includes a reference voltage circuit configured to maintain a reference voltage in proportion to actual circuit resistance values. Aspects of the invention also include dynamic compensation for variations in temperature.

Abstract: An oscillator is provided that includes an oscillating structure generating an output signal with a frequency that drifts as a function of a parameter of its environment, and a compensation circuit coupled to the oscillating structure. The oscillating structure has a ring structure that includes delay cells looped together, and the compensation circuit supplies a compensation signal to the oscillating structure. The compensation signal varies as a function of changes in the parameter in order to compensate for the drift in the frequency of the generated signal. This makes it possible to compensate for oscillator temperature drifts in the absence of a regulation loop.

Abstract: The shape of a crotch portion of a tuning fork of a quartz piece is controlled such that main surfaces of two sheets of original plates, which are made of quartz crystal and the main surfaces thereof are orthogonal to the direction of the Z axis, which is a crystal axis, are bonded so that the plus/minus directions of the X axis, which is another crystal axis, are made in a reverse relation to each other to form a quartz substrate, and masks for forming the outer shape, through which the surfaces of the quartz substrate are exposed, are formed on both front and back surfaces of the quartz substrate in a manner that the mask follows along the outer shape of the quartz piece and the width direction of the outer shape agrees with the X axis, and the quartz substrate is etched to form the outer shape of the quartz piece.

Abstract: The present invention provides a constant temperature oven type crystal oscillator for reducing the difference of frequency stability caused by controlling the temperature in the oscillator when detecting the change of the outside-air temperature and controlling the amount of generated heat of a heat source provided in the oscillator.

Abstract: Systems and methods are provided that compensate for frequency drift due to temperature variation without the need for a temperature sensor. In one embodiment, a navigation receiver with an integrated communication device receives a base station reference signal, which is used to periodically calibrate a local oscillator frequency. In another embodiment, the calibrated local oscillator frequency drives a counter that is used to provide code phase estimation at the start of satellite signal acquisition. To provide temperature compensation in one embodiment, the calibrated local frequency is used to drive one or more counters at different calibration rates (i.e., different time intervals between calibrations). Count values from these counters are used to determine compensation for frequency drift due to temperature variation based on predicted frequency drift variation patterns between calibrations.

Abstract: A real time clock assembly includes paired crystal oscillators that experience changes in frequency responsive to temperature. The differences in frequency changes between the paired crystal oscillators are utilized to determine a temperature utilized to compensate for those shifts in frequency. The predictability of frequency responsive to temperature variations by the paired crystal oscillators is utilized for the determination of temperature.

Abstract: Bias circuits to stabilize oscillation in ring oscillators, oscillators, and methods to stabilize oscillation in ring oscillators are provided. The ring oscillator includes a plurality of differential delay cells, each including a pair of input transistors, a pair of voltage-controlled resistors, and a common current source. The bias circuit includes a replica arm that includes a replica of one of the voltage-controlled resistors, and a resistor arm that includes a fixed resistor. The bias circuit supplies bias voltages to the differential delay cells such that ratio of voltage swing to bias current of the delay cell is kept constant by referring the ratio to the fixed resistor.

Abstract: A method of manufacturing a temperature compensated oscillator including the steps of assembling an oscillator in which an IC chip constituting a temperature compensation circuit with an oscillation circuit and a compensation data storage circuit, and a resonator for the oscillation circuit are mounted in a package; adjusting the resonator with an oscillation frequency of the oscillation circuit to a desired oscillation frequency in condition that the oscillator is kept at a reference temperature, in condition that a temperature compensation function of the temperature compensation circuit is disabled; sealing the resonator hermetically; creating temperature compensation data and storing it into the compensation data storage circuit; and enabling the temperature compensation function of the temperature compensation circuit.

Abstract: A voltage-controlled oscillator is provided that avoids use of any crystal resonator, or any resonator that is external to and not integrated upon the voltage-controlled oscillator monolithic substrate. The present oscillator can receive two or more parameters that would likely have an affect on the oscillator frequency, yet the oscillator includes compensating transfer functions that will remove, or correct for, that effect. Transfer functions involve electronic subsystems implemented in hardware or software that receive the input parameter that has changed from a nominal value, and will note the drift in output frequency, yet will compensate for that drift so that the output frequency remains near the nominal value. The voltage-controlled oscillator preferably is an LCVCO, and the transfer function outputs can be summed to take into account multiple parameter changes.

Abstract: A phase-locked loop includes a phase-to-digital converter portion as well as a novel correction portion. The phase-to-digital converter (PDC) portion outputs a stream of first phase error words. The novel correction portion receives the first phase error words and generates a stream of second phase error words that is supplied to a loop filter. The PDC portion has a phase-to-digital transfer function that exhibits certain imperfections. In a first example, the correction portion determines an average difference between pairs of first phase error words, and uses this average difference to normalize the first phase error words to correct for changes in PDC portion transfer function slope due to changes in delay element propagation delay. In a second example, the correction portion corrects for gain mismatches in PDC portion transfer function. In a third example, the correction portion corrects for offset mismatches in PDC portion transfer function.

Abstract: Architectures for compensating the frequency drift of an oscillator based frequency synthesizer circuit due to the change of temperature are disclosed. By applying a digitally controlled frequency word which represents the frequency difference between an output signal of a crystal oscillator and a temperature-compensated signal obtained from the output of a frequency synthesizer, the generated frequency signal is controlled so as to be temperature compensated over a wide temperature range. In one embodiment, a frequency locked loop is provided to perform functions to compensate for possible drifts in the reference signal. The frequency locked loop receives a digital frequency corrected control word based on at least a first parameter and a second parameter, wherein the first parameter is a combination of a fixed frequency control word and an automatic frequency correction word, and the second parameter is derived from an external source.

Abstract: Film bulk acoustic resonators (FBARS) have resonant frequencies that vary with manufacturing variations, but tend to be matched when in proximity on an integrated circuit die. FBAR resonant frequency is determined using a fractional-N synthesizer and comparing phase/frequency of an output signal from the fractional-N synthesizer to a reference. The reference may be derived from a low frequency crystal oscillator, an external signal source, or a communications signal.

Abstract: A method provides a temperature controlled frequency source. The method reduces the effects of temperature variations on an operating frequency of the temperature controlled frequency source by temperature compensating the temperature controlled frequency source. The temperature-controlled frequency source may be an Oven-Controlled crystal oscillator (DCXO) and the temperature-controlled frequency source may be a TCXO ASIC. Analago temperature compensation may be provided by generating zero to fourth-order polynomial Chebyshev functions of temperature.

Abstract: An oscillation circuit includes a constant current source, a current mirror circuit configured to receive a constant input current from the constant current source and to output a current proportional to the constant input current, a first inverter configured to be driven with a quartz resonator to oscillate, an operational amplifier configured to supply a power to the first inverter with a voltage equal to an input voltage thereof and a second inverter having a power supply terminal connected to the current mirror circuit and to the operational amplifier and configure to generate the input voltage for the operational amplifier.

Abstract: An ocscillator circuit having: a) a piezoelectric crystal connected to a surface; b) a variable frequency generator for generating a driving signal which is supplied to the crystal to cause the crystal to oscillate, thereby causing the surface to oscillate; and, c) an analyser for monitoring the phase shift between the voltage across the crystal and the current flowing through it and, in response generating an adjustment signal which relates to the difference between the oscillation frequency and a resonant frequency of the crystal, the variable frequency generator being responsive to the adjustment signal to vary the frequency of the driving signal to cause the crystal to oscillate at the resonant frequency.

Abstract: 1st to nth pairs of transistors (n=an odd number) are connected in parallel, and each pair of transistors has an upper transistor and a lower transistor connected in series. A point between the upper transistor and the lower transistor of a preceding pair of transistors is connected to a gate of the lower transistor of a subsequent transistor, and the point between the upper transistor and the lower transistor of nth pair of transistors is connected to the gate of the first lower transistor. A capacitor is inserted between the lower transistor and a direct power source. A current regulating circuit connected to gates of the upper transistors, wherein the current regulating circuit supplies a gate voltage to each gate of the each upper transistor.